Does the temperature affect the speed of a baseball?

Answer 1

Cold weather makes it harder to pitch, because your muscles get tight and cold. Warm weather lets you pitch harder and looser, but can wear you down quicker. Rain does not affect much unless it is a cold rain, although it can make your grip slick on the ball.

Answer 2

Well to put it simply, yes. Temperature affects how much friction the ball encounters when thrown or hit. The colder it is (theoretically) the slower the ball will move. But its not measurable when Baseball is being played because the difference in speed is so tiny.